Prognostic nomogram for resectable gastric cancer after preoperative chemotherapy to assist in decision-making for adjuvant chemotherapy: a retrospective study combined with external validation

Abstract

Abstract Background Neoadjuvant chemotherapy combined with radical gastrectomy is the standard treatment for resectable gastric cancer, but whether these patients can benefit from adjuvant chemotherapy remains unclear. Methods A total of 732 patients with initially diagnosed non-metastatic resectable gastric cancer between 2004 and 2016 were screened using the Surveillance, Epidemiology, and Results database of the National Cancer Institute of the United States and retrospectively analyzed. Among them, 366 patients received postoperative chemotherapy and 506 patients did not. The propensity score matching was used to balance the two groups of confounding factors, the Kaplan–Meier method was used for survival analysis, and the logrank test was used to compare the differences between the survival curves. The Cox proportional hazards regression model was used to screen independent prognostic factors and establish a nomogram survival prediction model. The patients were divided into high-, moderate-, and low-risk groups according to the overall survival prediction score generated by X-tile software based on the nomogram. Results Multivariate analysis showed that the independent prognostic factors of gastric cancer in the group not receiving chemotherapy were history, ypT stage, ypN stage, and examined lymph node count, which were included in the nomogram prediction model. The C-index for the model was 0.727 (95% confidence interval, 0.65056–0.80344). The patients were divided into three different risk level groups based on the nomogram prediction score. Low- and moderate-risk patients did not benefit from adjuvant chemotherapy, while high-risk patients did. Conclusion The nomogram model in the present study can effectively evaluate the prognosis of patients with resectable gastric cancer. In addition, postoperative chemotherapy can be recommended for high-risk patients, but not for low-risk patients.